Copy machine and method of electrostatic copying



J. ANTHES 3,459,477

COPY MACHINE AND METHOD OF ELECTROSTATIC COPYING Filed March 7, 1966 Aug. 5, 1969 3 Sheets-Sheet 1 INVENTOR.

N o JACOB ANTHES ATTORNEY.

3,459,477 COPY MACHINE AND METHOD OF ELECTROSTATIC COPYING Filed March 7, 1966 J. ANTHES Aug. 5, 1969 3 Sheets-Sheet 2 F I G. 6

'II'I'III'I'I'IIIIIIIIIIIJ 'I'IIII'I'IIIIIIIIIIIII' 'IIII'IIIII'II'I'IIIIIIII I I 11/ I INVENTOR. .mcoa mmss ATTORNEY.

United States Patent 3,459,477 COPY MACHINE AND METHOD OF ELECTROSTATIC COPYING Jacob Anthes, Philadelphia, Pa., assignor to Electrocopy Corporation, Philadelphia, Pa., a corporation of Delaware Filed Mar. 7, 1966, Ser. No. 541,419

Int. Cl. G03g 15/00 US. Cl. 355-12 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to photo copy machines and is more particularly directed to an improved electrostatic type of machine incorporating novel charging apparatus and including improved charging and exposure techniques.

The electrostatic method of reproducing or copying printed or written material has become quite popular during the past ten years and many machines utilizing the electrostatic method of reproduction have become readily available and commercially successful. Most of the prior art machines incorporate chargers to initially impress a uniform electrostatic charge upon a sheet of transfer paper. The next step in the copying process consists of projecting an image of the original sheet being copied upon the previously charged surface of the transfer sheet. Lens systems or reflecting systems or sometimes combinations of the two are employed for this purpose. In this manner, by utilizing the principles of electrostatic reproduction, an electrostatic image of the original will be formed upon the charged surface of the transfer sheet. The image containing transfer sheet is then introduced into a toner bath wherein the toner particles within the bath adhere to the charged surface of the transfer sheet in proportion to the retained electrostatic charge to thereby produce a visible toned image. The final Steps in the electrostatic copy process include passing the toned image containing transfer sheet through a drying process with additional heat being added as may be required to properly set the toner and to aflix the image.

In general terms, the instant invention incorporates a method of electrostatic copying that completely eliminates the need for and the expense of quality optical systems. The original sheet is placed contiguous with a previously charged transfer sheet and then the composite sheets areexposed to a source of illumination. The light source directs its rays directly through both thicknesses of paper without requiring aid from any auxiliary optical system. This method not only produces copies of acceptable quality and excellence, but also provides complete reliability inasmuch as there are no moving optical parts to require adjustment or service. Further, by eliminating all lens and projection mechanisms, an extremely inexpensive machine is thus provided which enables a substantial reduction in the manufacturing costs and consequently a reduction in the selling prices of the electrostatic copy machine.

A further innovation has been built into the present v Patented Aug. 5, 1969 ice copy machine in the area of the electrostatic charger. As will hereinafter be set forth in more detail, the transfer paper utilized may be of any well-known manufacture having one coated side. This paper is fed into the machine with the coated side facing upwardly, and in accordance with the instant method it was found that only the coated side need be charged. It is therefore possible to provide a charger having only a negatively charged upper half and that the positively charged lower half can be replaced with an inexpensive steel ground plate. In this manner, a considerable savings in construction costs has been realized without any sacrifice in the quality of the reproduction.

By means of the elimination of the lower positively charged portion of the electrostatic charger, the instant machine further lends itself to a method of simultaneously charging and exposing the transfer sheet by utilizing a lower steel ground plate that has been thoroughly perforated to permit the rays from the source of illumination to strike the lower surface of the original sheet. Simultaneously thereto, an electrostatic charge is impressed upon the upper treated surface of the transfer sheet to receive an electrostatic image of the original. In this manner, a compact, inexpensive novel method of electrostatic copying has been developed. It is thus seen that the instant invention can produce copies of acceptable quality and at the same time eliminate lens systems, reflecting systems, one-half of the electrostatic charger and the individual compartments previously required for the separate functions of charging and exposing.

It is therefore an object of the instant invention to provide an improved electrostatic copy machine of the type set forth.

It is another object of the instant invention to provide an improved method of electrostatic copying.

It is a further object of this invention to provide a novel electrostatic copy machine incorporating a reduced number of operating parts which thus greatly reduce the cost of construction.

It is a further object of this invention to provide an electrostatic copy machine designed to function without the aid of optical, projection or reflection systems.

It is a further object of this invention to provide a novel electrostatic copy machine incorporating internal construction compatible to accommodate a direct contact method of copying.

It is a further object of this invention to provide a novel electrostatic copy machine incorporating unique paper separating structure to direct the original and transfer sheets through respective separate channels.

It is a further object of this invention to provide an electrostatic copy machine incorporating a grounded steel plate in lieu of a positively charged component of an electrostatic charger.

It is a further object of this invention to provide an electrostatic c-opy machine incorporating a combined charging and exposing compartment.

It is a further object of this invention to provide a novel electrostatic copy machine featuring novel insulated paper guide channels.

It is another object of this invention to provide a novel electrostatic copy machine that features vacuum paper separating means arranged to avoid any interference with the copying process.

It is another object of this invention to provide a novel electrostatic copy machine that is simple in construction, inexpensive in manufacture and trouble-free in operation.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

FIG. 1 is a perspective view of the invention showing the relationship of image carrying original and the transfer sheet as they are introduced into the machine.

FIG. 2 is a perspective view of the invention showing the original and transfer sheet rejection following the copying process.

FIG. 3 is a diagrammatic cross sectional view of the invention.

FIG. 4 is a cross sectional view taken along line 44 of FIG. 3.

FIG. 5 is an enlarged diagrammatic view of the paper separating means of FIG. 3.

FIG. 6 is a cross section taken along line 6-6 of FIG. 5.

FIG. 7 is a cross section taken along line 7-7 of FIG. 5.

FIG. 8 is a detail cross sectional view showing the paper intake channels.

FIG. 9 is a diagrammatic cross sectional of a modified form of the invention.

FIG. 10 is a cross section taken along line 1010 of FIG. 9.

Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of my invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.

Referring now to the drawings, I show an electrostatic copy machine 10 designed in accordance with the instant invention. An original sheet of paper 16 containing an image in the form of printing or writing on one side 18 thereof is fed into the lower intake channel 12 with the side to be copied facing up. A transfer sheet 24 having one surface 26 thereof coated with a light sensitive material such as zinc oxide is simultaneously introduced into the upper intake channel 20 with the coated surface 26 similarly facing up.

As best seen in FIG. 3, the transfer sheet 24 follows a path directly beneath the negatively charged half 32 of an electrostatic charger f0 conventional design wherein an electrostatic charge is impressed upon the sensitized surface 26. Simultaneously, the image carrying sheet 16 bypasses the charger half 32. The sheets 16, 24 meet at the illumination chamber input rollers 34, 36 which cooperate to squeeze the sheets together and to urge them forwardly together into the illumination chamber 38.

When the original sheet 16 and the transfer sheet have been inserted into the channels 12, 20 to the position indicated in FIG. 1, the operating motor circuit (not shown) may be energized to operate the machine in the usual manner. This also energizes the charger half 32 and rotates the driving rollers 34, 36 to urge the sheets of paper 16, 24 into the interior of the machine 10 therebetween. The input rollers 34, 36 simultaneously receive the image carrying original sheet 16 from the lower channel 12 and the electrostatically charged transfer sheet 24 from the upper channel 20. The rollers 34, 36 operate to both squeeze the sheets 16, 24 together and to urge them into the chamber 38 for exposure to light rays 64 from an upwardly facing light source 66, which may be vertically adjustable in any well known manner to properly vary the light intensity as required. It should be noted that the image containing surface 18 of the original sheet 16 faces upwardly and contacts the lower surface 28 of the transfer sheet 24. The treated surface 26 of the transfer sheet also faces upwardly and thus the light rays 64- from the light source 6-6 must penetrate two thicknesses of paper in order to impress the image of the original upon the sensitized surface of the transfer sheet. In order to produce a copy of acceptable quality and sharpness, the thickness of the transfer sheet should be approximately .002 to .005 inch. It will be appreciated that the image surface 18 is separated from the sensitized surface 26 only by the thickness of the transfer sheet 24 and that a positive impression can thus be formed by utilizing the principles of direct sheet contact and shooting the light rays through both sheets. As the thickness of the transfer sheet 24 decreases, the image surface 18 approaches the sensitized surface 26 and the sharpness of the reproduction will increase.

A unique paper separating arrangement may be observed by referring to FIGS. 3, 4 and 5 wherein a pair of transverse suction ducts 68, 70 cooperate to pull the sheets 16, 24 respectively into the original sheet ejection channel 42 and the toner bath channel 40 by urging the sheets against the respective channel deflectors 44, 46. The ducts 68, 70 transversely lie respectively .above and below the horizontal plane of travel of the sheets 16, 24 as they pass through the illumination chamber and are provided with inwardly facing, transverse suction slots 44, 46 which are positioned to respectively attract the sheets 24, 16. The ducts 68, 70 connect to the suction inlet 48 of the dryer fan 50 through a common air conduit 52 or optionally may have individual connections. A balancing damper 54 interiorly regulates the volume of air passing through the conduit 52 to permit ready adjustment of the suction forces available at the intake slots 44, 46.

As best seen in FIG. 3, after leaving the illumination chamber 38 under the urging of the output rollers 96, 98, the original sheet 16 separates from the transfer sheet 24 by means of the suction ducts 68, 70 as hereinabove described and leaves the machine 10 through the bottom ejection slot 14. The transfer sheet 24 carrying the impressed electrostatic image on its sensitized surface 26 passes downwardly into a toner bath 94 wherein a toned image is formed in the usual manner. The transfer sheet is then driven by a pair of ejection rollers 100, 102 through a drying channel 104 wherein the sheet is dried and heated as required to properly affix the toner and dry the copy prior to delivery of the completed copy through the transfer sheet ejection slot 22.

Referring now to FIG. 3, I show a single upper half, negative charger 32 being employed for charging purposes. As has previously been set forth, the transfer sheet 24 is fed into the transfer sheet intake slot 20 with the coated surface 26 facing upwardly. By applying a negative voltage of approximately 3500 volts to the upper charger half, a satisfactory electrostatic charge can be applied to the coated surface 26 as it passes under the charger 32. In order to complete the charging operation, a steel ground plate 72 must be substituted for the usual positive lower half of an electrostatic charger. As can be seen in the drawing, the ground plate 72 also serves to separate the original sheet 16 from the transfer sheet 24 and defines the original intake slot 12 from the transfer intake slot 20. Once the sheets are aligned in their respective intake channels the operator may then start the copying process. It should be noted that the original sheet intake path and the transfer sheet intake path are substantially parallel and for all practical purposes, equal in length. This construction greatly simplifies the copying process, inasmuch as once the sheets are aligned, they will effectively remain aligned and in register during the course of travel through the charging chamber 74 and the illumination chamber 38. The ground plate 72 extends outside of the machine and forms a generally horizontal divider to define the original sheet intake slot 12 and the transfer sheet intake slot 20. A larger guide table 76 mounts below the ground plate 72 and carries a vertical guide 78 along the sides to facilitate the paper feed procedure. A paper guide plate 80 mounts above the ground plate to form an upper slot to receive the contact transfer sheet 24. The original sheet 16 feeds under the ground plate 72, with the image surface 26 facing upwardly and the blank surface in contact with the guide table 76.

The single sided negatively charged electrostatic charger 32 as above described would ordinarily not function because the electrostatic paper 24, once charged only negatively, would cling tightly to the ground plate due to the difference in polarity of the charges, and could not be fed through. To completely eliminate this difiiculty and to solve the problem, I have found that a layer of felt 82 approximately one sixteenth of an inch thick, applied to the top side of the ground plate 72 acts as a complete static charge insulator, thus permitting the paper to pass smoothly through the charger. The upper paper guide plate 80 is similarly insulated by applying a layer of felt to the undersurface to thereby eliminate a slight sticking tendency that still remains, due to the static charge spreading forwardly over the paper surface. It is thus seen that I have provided a felt lined transfer sheet intake channel 20 to completely insulate static charges and thereby to permit smooth flow during the copying process. Other materials have been tried for insulating purposes, but none have proved as effective as the felt. Ordinary thickly woven cloth was found to be next best, but several thicknesses were required to produce satisfactory results.

As seen in FIG. 8, the felt 82 is applied to the ground plate 72 leaving a transverse space 84 therebetween. A stainless steel strip 86 transversely extends across the entire width of the ground plate 72 and bends upwardly towards the charger 32. This construction forces the zinc coated side 26 of the electrostatic paper 24 to bend up and over the strip 86 as it is fed towards the charger 32. I have found that this construction provides a more ,consistent and uniform charge over the electrostatic paper, particularly on the first inch or two at the top of the sheet. This construction finds further utility in the dissipation of a slight shock that sometimes was formerly transmitted along the paper to the operators fingers.

Referring now to FIG. 9, I show a further modification of my direct contact electrostatic copy machine in which the ground plate 72 of FIG. 3 is again utilized in lieu of the positive half of a charger. Generally parallel original sheet and transfer sheet intake channel 12, 20, and the ground plate 72 are employed in the same manner as hereinabove set forth. In this modification however, the previously separate illumination chamber 38 and the charging chamber 74 have been eliminated and in their place, a single charging and exposing enclosure 88 has been established. A light source 66 such as a conventional photographic fluorescent tu'be mounts below the ground plate 72 and may have vertical height adjusting mechanism in any well-known manner to permit the light intensity to be varied as required by the quality of the copy material. An upper negative half 32 of a high voltage charger is positioned within the enclosure 88 above the ground plate 72 and is generally vertically aligned with the tube 66. Felt layers 82 line the bottom of the paper guide and the top of the ground plate 72 in the same manner as hereinabove set forth.

As best observed in FIG. 10, the ground plate 72 within the enclosure 88 is constructed of a transverse strip of perforated metal and the copy paper 24 is passed between the half charger 32 and the perforated metal ground plate 72. It is thus evident that the electrostatic charge is impressed upon the coated surface of the electrostatic paper at the same time that the exposure is taking place on the other side as the light rays 64 pass through the original sheet .16 and the transfer sheet 24 to impinge upon the simultaneously charged face of the transfer sheet. The guide table extension 92 within the enclosure 88 must be fabricated of transparent material to permit the light rays 64 to pass through and strike the sheet 16.

It is of great importance that the hole pattern 90 on the perforated metal of the ground plate 72 be such that it provides evenly distributed light exposure on the paper as the paper moves under it. The holes must therefore be diagonally arranged in relation to the direction of paper travel as indicated. A diagonally positioned, course mesh screen could also be utilized for this purpose. If the perforated metal is such that most of the metal has been punched away, thereby leaving a pattern of closely spaced holes, the charge on the paper will be decreased, and the exposure factor will be increased. Smaller holes or wider spacing between holes will produce a lesser exposure and greater charge. The optimum balance of the variables must be determined by the paper and toner characteristics and by the speed of the paper travel.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereafter claimed.

What is claimed is:

1. In .an electrostatic copy machine receiving an original sheet and a transfer sheet, the combination of (A) an original sheet entrance channel and a transfer sheet entrance channel,

(1) said channels being disposed in substantially parallel, horizontal, spaced relation;

(B) charging means impressing an electrostatic charge upon one surface of the said transfer sheet;

(1) the said charging means including a positive steel ground plate positioned below the said transfer sheet channel; and

(a) the ground plate forming the horizontal separation between the said channels;

(C) exposing means directing light rays through both of the said sheets,

(1) said light rays producing an electrostatic image upon the said charged surface of the tranfser sheet;

(D) paper separating means separating the said sheets upon completion of the exposing operations; and

(E) toner bath means producing a toned image upon the said charged and exposed surface of the transfer sheet.

2. The invention of claim 1 and electrostatic charge insulating means applied interiorly to the said transfer sheet entrance channel.

3. The invention of claim 1 and electrostatic insulating means affixed to the said transfer sheet entrance channel, a portion of said insulating means lining the bottom of the said channel and a portion of the said means lining the top of the said channel.

4. The invention of claim 1 and electrostatic insulating means aflixed to the said transfer sheet entrance channel, a portion of said insulating means lining the bottom of the said channel and a portion of the said means lining the top of the said channel, the said bottom portion of the insulating means being transversely cut into two portions to define a forward insulation and a rearward insulation having a transverse gap therebetween.

5. In an electrostatic copy machine receiving an original sheet and a transfer sheet, the combination of (A) an original sheet entrance channel and a transfer sheet entrance channel;

(1) said channels being disposed in substantially parallel, horizontal, spaced relation; and

(2) said original sheet entrance channel underlying the said transfer sheet entrance channel;

(B) charging means impressing an electrostatic charge upon one surface of the said transfer sheet;

( 1) said charging means including an upper negative charger disposed above the said transfer sheet channel;

(C) exposing means directing light rays through both of the said sheets to expose the said charged surface with an electrostatic image of the original;

(1) said exposing means being vertically spaced from the said charging means; and

(2) said exposing means directing light rays through a portion of the said charging means;

(D) a steel ground plate forming the floor of one said sheet entrance channel;

( 1) the said ground plate being perforated throughout to permit passage of light rays from the said exposing means;

(E) and toner bath means producing a toned image upon the said charged and exposed surface of the said transfer sheet.

6. The invention of claim 5 wherein the said perforations being randomly arranged to permit full even exposure of the said transfer sheet as it is passed through the copy machine.

7. The invention of claim 5 wherein the said transfer sheet entrance channel is lined with electrostatic insulating material, and wherein the channel floor insulating material is transversely divided to define a transverse opening in the said insulating material.

References Cited UNITED STATES PATENTS 15 JOHN M. HORAN, Primary Examiner 

